Maybe I’m just being more sensitive to the noise lately – or maybe mufflers wear out internally?

I am wondering if anyone has had a noticeable drop in interior cabin noise at freeway speeds when they have replaced the center resonator and the rear muffler? If so, could you please say how much of a difference there was, and what was the condition of the exhaust system that you replaced?

My car’s exhaust system is original (1984 300D, 220,000 miles) and there are not any large holes or anything, but it looks like corrosion is just starting to surface. I am wondering if the internal baffles start to rot out & cause a progressive increase in noise, especially when the engine is under load. There is a LARGE difference in noise levels when traveling 70mph and coasting versus cruising. The noise is not just the injection pump and injectors – it is a pretty significant roaring.

Any input would be greatly appreciated.